Unlike wired communications systems, wireless communications systems transmit radio signals in a broadcasting manner. Thus, in a mobile radio communications network with multiuser settings, there always exists a risk of wiretapping by internal users who share the same resources. Conventionally, in establishing security of the wireless communications systems in a network layer, a wiretapper is allowed to receive a transmitted data. Accordingly, if the wiretapper devotes some time to analyzing codes of the received data, leakage of confidential or personal information may occur anytime. Thus, in a modern society where security issue is getting more important, there has been a demand for a technology that enables blocking reception of transmitted data by a wiretapper.
Meanwhile, in establishing security of the wireless communications system in a physical layer, by blocking a wiretapper on a network from receiving information transmitted from a user, no data to be restored or analyzed may be provided to the wiretapper. To this end, there has been a demand for a method for establishing security of the network in the physical layer of the wireless communications system.